Scientists have detected faint traces of methane gas above the dwarf planet Makemake, located far beyond Pluto in our solar system. This finding, made using the James Webb Space Telescope, indicates that Makemake may possess an ultra-thin atmosphere or release methane from its frozen surface in plumes. This discovery challenges previous assumptions about the icy body, suggesting it is not merely a relic, but an active celestial world.
The research, led by the Southwest Research Institute, is set to be published in The Astrophysical Journal Letters. According to Silvia Protopapa, the lead author, “Makemake is one of the largest and brightest icy worlds beyond Neptune, and its surface is dominated by frozen methane.” The Webb telescope’s observations reveal that methane is also present in the gas phase above the surface, adding to the planet’s intrigue.
Makemake, which was discovered two decades ago, is named after the Rapanui god of fertility. At only 890 miles wide, it is two-thirds the size of Pluto and is situated approximately 4.25 billion miles from the sun. Its immense distance means that it takes about 305 Earth-years to complete one orbit around the sun. In 2016, astronomers identified a moon orbiting Makemake, further enhancing its significance in the study of the outer solar system.
The James Webb Space Telescope has provided unprecedented insights into Makemake’s surface chemistry. The observations indicate that portions of the dwarf planet’s frozen surface are transitioning into gas. When sunlight interacts with gas molecules, they emit a faint glow, which is how the presence of methane was detected. The origin of this methane remains uncertain. Some scientists speculate that it may have been formed through water–rock chemistry inside the dwarf planet, while others suggest it could be remnants from the early solar system.
Over time, sunlight and radiation decompose methane into more complex molecules, such as ethane, ethylene, and acetylene, which have already been observed on Makemake. Nevertheless, researchers have yet to determine whether the detected gas originates from an atmosphere or from plume-like clouds. The faintness of any potential atmosphere is notable, being billions of times thinner than Earth’s and much weaker than that of Pluto.
The possibility of methane bursts emerging from the surface of Makemake, similar to the geysers on Saturn’s moon Enceladus, is particularly intriguing. “If this scenario is confirmed,” said Emmanuel Lellouch, a co-author of the study, “Makemake would join the small handful of outer solar system bodies where surface–atmosphere exchanges are still active today.” Protopapa noted that if methane is not forming an atmosphere, it could be releasing “a few hundred kilograms” of methane bursts every second, akin to the activity observed on Enceladus.
Interestingly, data from Webb and other infrared telescopes indicate that certain regions on Makemake are unexpectedly “warm,” measuring around -190 degrees Fahrenheit. Despite this, researchers have not yet found direct evidence of gas escaping from these warm spots. Though it might be tempting to infer a methane-based weather cycle on Makemake, co-author Ian Wong cautions against drawing premature conclusions. “While the temptation to link Makemake’s various spectral and thermal anomalies is strong,” Wong stated, “establishing the mechanism driving the volatile activity remains a necessary step toward interpreting these observations.”
As scientists continue to explore Makemake, these findings underscore the evolving nature of our understanding of distant celestial bodies. The possibility of active geological processes, along with the intriguing presence of methane, positions Makemake as a significant subject of study in the ongoing exploration of our solar system’s outer reaches.
